Heat assisted magnetic recording (HAMR) media with Curie temperature reduction layer
HAMR media with a magnetic recording layer having a reduced Curie temperature and methods of fabricating the HAMR media are provided. One such HAMR medium includes a substrate, a heat sink layer on the substrate, an interlayer on the heat sink layer, and a multi-layer magnetic recording layer on the interlayer. In such case, the multi-layer magnetic recording layer includes a first magnetic recording layer including an alloy selected from FePtX and CoPtX, where X is a material selected from the group consisting of Cu, Ni, and combinations thereof, a second magnetic recording layer on the first magnetic recording layer and having at least one material different from the materials of the first magnetic recording layer, and a third magnetic recording layer on the second magnetic recording layer and having at least one material different from the materials of the first magnetic recording layer.
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Magnetic storage systems, such as a hard disk drive (HDD), are utilized in a wide variety of devices in both stationary and mobile computing environments. Examples of devices that incorporate magnetic storage systems include desktop computers, portable notebook computers, portable hard disk drives, digital versatile disc (DVD) players, high definition television (HDTV) receivers, vehicle control systems, cellular or mobile telephones, television set top boxes, digital cameras, digital video cameras, video game consoles, and portable media players.
A typical disk drive includes magnetic storage media in the form of one or more flat disks. The disks are generally formed of two main substances, namely, a substrate material that gives it structure and rigidity, and a magnetic media coating that holds the magnetic impulses or moments that represent data in a recording layer within the coating. The typical disk drive also includes a read head and a write head, generally in the form of a magnetic transducer which can sense and/or change the magnetic fields stored on the recording layer of the disks.
Energy/Heat Assisted Magnetic Recording (EAMR/HAMR) systems can potentially increase the areal density of information recorded magnetically on various magnetic media. For example, to achieve magnetic information storage levels beyond 1 terabit per square inch, smaller grain size (e.g., less than 6 nm) media may be required. Such designs can demand higher Ku materials for a recording layer to sustain thermal stability, such as L10 ordered FePt alloys. Due to high anisotropy, FePt media is not writable with conventional recording heads. Therefore, either an exchange coupled composite media structure or heat-assisted magnetic recording (HAMR) are generally needed. HAMR media generally includes a magnetic recording layer and a heat sink positioned beneath the magnetic recording layer. To facilitate efficient HAMR, including the use of minimal laser power to achieve heat assisted writing and reading of information on the media, it is often necessary to dissipate heat and/or light energy from the magnetic recording layer. Typically, this is achieved to a certain degree by the heat sink layer. However, the use of minimal and/or reduced laser power may also be helpful.
It has recently been found that a laser power reduction is beneficial for lifetime improvement in heat assisted magnetic recording (HAMR) applications. More specifically, conventional HAMR systems including HAMR media based on L10 FePt type materials suffer from short lifetimes. Such short lifetimes often result from being unable to decrease laser power (e.g., without signal to noise ratio (SNR) penalties) during HAMR recording. In order to reduce laser power requirements and lower writing temperatures, it is useful to adjust the Curie temperature of the FePt magnetic recording layer. HAMR media with magnetic recording layers having reduced Curie temperatures are described herein and involve a low cost and fabrication friendly approach to control the Curie temperature of the magnetic recording layer for improvement of SNR characteristics and laser power reduction.
Referring now to the drawings, HAMR media with a magnetic recording layer having a reduced Curie temperature and methods of fabricating the HAMR media are illustrated. One such HAMR medium includes a substrate, a heatsink layer on the substrate, an interlayer on the heatsink layer, and a multi-layer magnetic recording layer on the interlayer. In such case, the multi-layer magnetic recording layer includes a first magnetic recording layer including an alloy selected from FePtX and CoPtX, where X is a material selected from Cu, Ni, and combinations thereof, a second magnetic recording layer on the first magnetic recording layer and having at least one material different from the materials of the first magnetic recording layer, and a third magnetic recording layer on the second magnetic recording layer and having at least one material different from the materials of the first magnetic recording layer. In one aspect, a method for fabricating this HAMR medium is described. The HAMR media described herein can provide a reduced Curie temperature as compared to current HAMR media designs, thereby reducing HAMR laser power and extending lifetimes of HAMR components including the media. In addition, the HAMR media described herein can provide a low cost and highly manufacturable approach for improvement of SNR while reducing the HAMR laser power.
In operation, a spindle motor (not shown) rotates the spindle assembly 104, and thereby rotates disk 102 to position head 108 at a particular location along a desired disk track 107. The position of head 104 relative to disk 102 may be controlled by position control circuitry 110.
In operation, the laser 114 is configured to generate and direct light energy to a waveguide (possibly along the dashed line) in the slider which directs the light to a near field transducer (NFT) near the air bearing surface (e.g., bottom surface) 108c of the slider 108. Upon receiving the light from the laser 114 via the waveguide, the NFT generates localized heat energy that heats a portion of the media 102 near the write element 108a and the read element 108b.
The first MRL 310a may be made of an alloy selected from FePtX and CoPtX, where X is a material selected from Cu, Ni, and combinations thereof. In one embodiment, the first MRL 310a includes a number of magnetic grains segregated by carbon segregants, where the magnetic grains are made of the alloy. In one embodiment, X may be Cu. In one embodiment, X has a atomic percentage of 1 to 30 percent or about 1 to 30 percent. In another embodiment, X has a atomic percentage of 7.5 to 10 percent or about 7.5 to 10 percent. In one embodiment, the first MRL 310a includes, or consists of, L10 FePtCAgX where X is Cu and has an atomic percentage of 1 to 30 percent. In one embodiment, the first MRL 310a is made of an alloy selected from FePtXX2 and CoPtXX2, where X2 is a material selected from the group consisting of Ag, C, BN, and combinations thereof. In several embodiments, the first MRL 310a is magnetic and configured to remain magnetic at temperatures sufficiently high to enable information to be recorded to the multi-layer MRL 310. In several embodiments, the first MRL 310a may include one or more segregant additives such as Cu, Ag, C, Ni, BN.
In several embodiments, the second MRL 310b may have at least one material different from the materials of the first MRL 310a. For example, in one embodiment, the second MRL 310b may be made of an alloy selected from L10 FePtX3 and L10 CoPt X3, where X3 is a material selected from BN, C, and combinations thereof. In such case, the BN, C materials may act as segregant additives. In one embodiment, the second MRL 310b may be made of FePtCBN.
In a number of embodiments, the third MRL 310c may have at least one material different from the materials of the first MRL 310a. For example, in one embodiment, the third MRL 310c may be made of an alloy selected from L10 FePtX4 and L10 CoPtX4, where X4 is a material selected from the group consisting of BN, SiO2, B2O3, ZrO2, and combinations thereof. In such case, the BN, SiO2, B2O3, ZrO2 materials may act as segregant additives. In several embodiments, the third MRL 310c includes at least one material different from the materials of the second MRL 310b. In one embodiment, the third MRL 310c may be made of FetPtBNSiO2.
In several embodiments, the Curie temperature of the first MRL 310a is lower than the Curie temperature of either the second MRL 310b or the third MRL 310c. In such case, the overall Curie temperature of the multi-layer MRL 310 may be reduced as compared to conventional magnetic recording media. In several embodiments, the first MRL 310a, the second MRL 310b, and the third MRL 310c operate collectively (e.g., effectively operate as a single MRL or entity) to enable information to be recorded to the multi-layer magnetic recording layer 310. For example, in one embodiment, one bit of information may collectively be stored within one grain from each MRL, where the grains are positioned at roughly the same horizontal position along the layers and may collectively act like a single vertically oriented grain extending through all three of the layers. This can be the case even if the grains on each MRL are physically distinct based on having different materials. In other embodiments, the one single grain may be replaced by multiple grains on any given layer to store the single bit of information.
In one embodiment, the substrate 302 can be made of one or more materials such as an Al alloy, NiP plated Al, glass, glass ceramic, and/or combinations thereof. In one embodiment, the adhesion layer 304 can include one or more materials such as CrTi, CrTa, NiTa, CoCrTaZr, CoFeZrBCr, CoTaZr, CoFeTaZr, CoCrWTaZr, CoCrMoTaZr, CoZrWMo, combinations thereof, and/or other suitable materials known in the art.
In one embodiment, the heat sink layer 306 can be made of one or more materials such as Ag, Al, Au, Cu, Cr, Mo, Ru, W, CuZr, MoCu, AgPd, CrRu, CrV, CrW, CrMo, CrNd, NiAl, NiTa, combinations thereof, and/or other suitable materials known in the art.
In one embodiment, the interlayer 308 provides a preselected texture for the multi-layer MRL 310. The interlayer 308 can be made of MgO, TiN, TiC, amorphous under layer such as CoCrTaZr, CoWZrMo, body centered cubic (bec) Cr or Cr alloy, W or W alloy, M or Mo alloy, B2RuAl, NiAl, or other suitable materials. In one embodiment, the interlayer 308 is made of MgO and the amorphous under layer is made of CoWZrMo.
In one embodiment, the capping layer 312 is made of Co, Pt, or Pd. In one embodiment, the capping layer 312 can be a bi-layer structure having a top layer including Co and a bottom layer including Pt or Pd. In addition to the Co/Pt and Co/Pd combinations of top layer and the bottom layer, specific combinations of the top layer materials and the bottom layer materials may include, for example, Co/Au, Co/Ag, Co/Al, Co/Cu, Co/Ir, Co/Mo, Co/Ni, Co/Os, Co/Ru, Co/Ti, Co/V, Fe/Ag, Fe/Au, Fe/Cu, Fe/Mo, Fe/Pd, Ni/Au, Ni/Cu, Ni/Mo, Ni/Pd, Ni/Re, etc. In additional embodiments, top layer materials and bottom layer materials include any combination of Pt and Pd (e.g., alloys), or any of the following elements, alone or in combination: Au, Ag, Al, Cu, Ir, Mo, Ni, Os, Ru, Ti, V, Fe, Re, and the like.
In one embodiment, the overcoat layer 314 is made of carbon. In one embodiment, the lubricant layer 316 is made of a polymer based lubricant. In one embodiment, the HAMR magnetic medium 300 further includes a thermal resistive layer between the heat sink layer 306 and the interlayer 308. The thermal resistive layer can be made of oxides such as ZrO2, SiO2, HfO2, Mg2SiO4, and/or other materials with low thermal conductivity.
The terms “above,” “below,” and “between” as used herein refer to a relative position of one layer with respect to other layers. As such, one layer deposited or disposed above or below another layer may be directly in contact with the other layer or may have one or more intervening layers. Moreover, one layer deposited or disposed between layers may be directly in contact with the layers or may have one or more intervening layers.
In one embodiment, the first magnetic recording layer (e.g., M1 or first MRL 310a of
In one embodiment, the process can perform the sequence of actions in a different order. In another embodiment, the process can skip one or more of the actions. In other embodiments, one or more of the actions are performed simultaneously. In some embodiments, additional actions can be performed.
In several embodiments, the deposition of such layers can be performed using a variety of deposition sub-processes, including, but not limited to physical vapor deposition (PVD), sputter deposition and ion beam deposition, and chemical vapor deposition (CVD) including plasma enhanced chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD) and atomic layer chemical vapor deposition (ALCVD). In other embodiments, other suitable deposition techniques known in the art may also be used.
While the above description contains many specific embodiments of the invention, these should not be construed as limitations on the scope of the invention, but rather as examples of specific embodiments thereof. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their equivalents.
The various features and processes described above may be used independently of one another, or may be combined in various ways. All possible combinations and sub-combinations are intended to fall within the scope of this disclosure. In addition, certain method, event, state or process blocks may be omitted in some implementations. The methods and processes described herein are also not limited to any particular sequence, and the blocks or states relating thereto can be performed in other sequences that are appropriate. For example, described tasks or events may be performed in an order other than that specifically disclosed, or multiple may be combined in a single block or state. The example tasks or events may be performed in serial, in parallel, or in some other suitable manner. Tasks or events may be added to or removed from the disclosed example embodiments. The example systems and components described herein may be configured differently than described. For example, elements may be added to, removed from, or rearranged compared to the disclosed example embodiments.
Claims
1. A magnetic recording medium for heat assisted magnetic recording, the medium comprising:
- a substrate;
- a heatsink layer on the substrate;
- an interlayer on the heatsink layer; and
- a multi-layer magnetic recording layer on the interlayer and comprising: a first magnetic recording layer comprising an alloy selected from the group consisting of FePtX and CoPtX, where X is a material selected from the group consisting of Cu, Ni, and combinations thereof; a second magnetic recording layer on the first magnetic recording layer and having at least one element different from materials of the first magnetic recording layer; and a third magnetic recording layer on the second magnetic recording layer and having at least one element different from the materials of the first magnetic recording layer, and at least one element different from materials of the second magnetic recording layer, wherein the first magnetic recording layer further comprises a plurality of magnetic grains segregated by carbon segregants, wherein the plurality of magnetic grains comprise the alloy such that a heat transfer from the second magnetic recording layer to the heatsink layer is greater than a lateral heat transfer within the first magnetic recording layer.
2. The medium of claim 1:
- wherein the first magnetic recording layer is magnetic and configured to remain magnetic at temperatures sufficiently high to enable information to be recorded to the multi-layer magnetic recording layer.
3. The medium of claim 1, wherein the first magnetic recording layer, the second magnetic recording layer, and the third magnetic recording layer operate collectively to enable information to be recorded to the multi-layer magnetic recording layer.
4. The medium of claim 1:
- wherein the first magnetic recording layer comprises an alloy selected from the group consisting of FePtXX2 and CoPtXX2, where X2 is a material selected from the group consisting of Ag, C, BN, and combinations thereof;
- wherein the second magnetic recording layer comprises an alloy selected from the group consisting of L10 FePtX3 and L10 CoPt X3, where X3 is a material selected from the group consisting of BN, C, and combinations thereof; and
- wherein the third magnetic recording layer comprises an alloy selected from the group consisting of L10 FePtX4 and L10 CoPt X4, where X4 is a material selected from the group consisting of BN, SiO2, B2O3, ZrO2, and combinations thereof.
5. The medium of claim 1, wherein X has a atomic percentage of 1 to 30 percent.
6. The medium of claim 1, wherein X is Cu.
7. The medium of claim 1, wherein the first magnetic recording layer comprises L10 FePtCAgX where X is Cu and has a atomic percentage of 1 to 30 percent.
8. The medium of claim 1, further comprising:
- an adhesion layer on the substrate, wherein the heatsink layer is on the adhesion layer;
- a thermal resistive layer on the heatsink layer, wherein the interlayer is on the thermal resistive layer;
- a cap layer on the multi-layer magnetic recording layer; and
- an overcoat layer on the cap layer.
9. The medium of claim 1, wherein a curie temperature of the first magnetic recording layer is less than a curie temperature of either the second magnetic recording layer or the third magnetic recording layer.
10. The apparatus of claim 1, wherein the first magnetic recording layer comprising an alloy selected from the group consisting of FePtCuAg and CoPtCuAg.
11. A method for manufacturing a magnetic recording medium for heat assisted magnetic recording, the method comprising:
- providing a substrate;
- providing a heatsink layer on the substrate;
- providing an interlayer on the heatsink layer; and
- providing a multi-layer magnetic recording layer on the interlayer and comprising: a first magnetic recording layer comprising an alloy selected from the group consisting of FePtX and CoPtX, where X is a material selected from the group consisting of Cu, Ni, and combinations thereof; a second magnetic recording layer on the first magnetic recording layer and having at least one element different from materials of the first magnetic recording layer; and a third magnetic recording layer on the second magnetic recording layer and having at least one element different from the materials of the first magnetic recording layer, and at least one element different from materials of the second magnetic recording layer, wherein the first magnetic recording layer further comprises a plurality of magnetic grains segregated by carbon segregants, wherein the plurality of magnetic grains comprise the alloy such that a heat transfer from the second magnetic recording layer to the heatsink layer is greater than a lateral heat transfer within the first magnetic recording layer.
12. The method of claim 11:
- wherein the first magnetic recording layer is magnetic and configured to remain magnetic at temperatures sufficiently high to enable information to be recorded to the multi-layer magnetic recording layer.
13. The method of claim 11, wherein the first magnetic recording layer, the second magnetic recording layer, and the third magnetic recording layer operate collectively to enable information to be recorded to the multi-layer magnetic recording layer.
14. The method of claim 11:
- wherein the first magnetic recording layer comprises an alloy selected from the group consisting of FePtXX2 and CoPtXX2, where X2 is a material selected from the group consisting of Ag, C, BN, and combinations thereof;
- wherein the second magnetic recording layer comprises an alloy selected from the group consisting of L10 FePtX3 and L10 CoPt X3, where X3 is a material selected from the group consisting of BN, C, and combinations thereof; and
- wherein the third magnetic recording layer comprises alloy selected from the group consisting of L10 FePtX4 and L10 CoPt X4, where X4 is a material selected from the group consisting of BN, SiO2, B2O3, ZrO2, and combinations thereof.
15. The method of claim 11, wherein X has a atomic percentage of 1 to 30 percent.
16. The method of claim 11, wherein X is Cu.
17. The method of claim 11, wherein the first magnetic recording layer comprises L10 FePtCAgX where X is Cu and has a atomic percentage of 1 to 30 percent.
18. The method of claim 11, further comprising:
- providing an adhesion layer on the substrate, wherein the heatsink layer is on the adhesion layer;
- providing a thermal resistive layer on the heatsink layer, wherein the interlayer is on the thermal resistive layer;
- providing a cap layer on the multi-layer magnetic recording layer; and
- providing an overcoat layer on the cap layer.
19. The method of claim 11, wherein a curie temperature of the first magnetic recording layer is less than a curie temperature of either the second magnetic recording layer or the third magnetic recording layer.
20. The method of claim 11, wherein the first magnetic recording layer comprising an alloy selected from the group consisting of FePtCuAg and CoPtCuAg.
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Type: Grant
Filed: Sep 25, 2015
Date of Patent: Jul 27, 2021
Assignee: WESTERN DIGITAL TECHNOLOGIES, INC. (San Jose, CA)
Inventors: Hua Yuan (San Jose, CA), Antony Ajan (San Jose, CA), Oleg Krupin (Mountain View, CA), B. Ramamurthy Acharya (Fremont, CA)
Primary Examiner: Holly Rickman
Assistant Examiner: Lisa Chau
Application Number: 14/865,501
International Classification: G11B 5/66 (20060101); H01F 41/22 (20060101); G11B 5/65 (20060101); G11B 5/73 (20060101); G11B 5/00 (20060101);